Extract string with regexp()

I have a variable that stores a string. The string contains letters, numbers, underscores and symbols (there is no specific order, and not just once). Now I want to extract the string through regexp(). The extracted string should start with letters, numbers and underscores and end with letters or numbers, but the suffix needs to exclude '_' or '_in' or '_out' or '_out[]', how can I do that? Thanks.

str_new = regexp(str_old,'[^$^|]\w*_*\w*[^_^_out^_in^_out[]^_in[]]','match')

I want to use '^' to exclude string in '[ ]' , but it is distinguish only one letter or another...

eg:

str_old = '$abc_in'

str_new = abc

str_old = 'def_in_hij_out[]'

str_new = 'def_in_hij'

str_old = 'xyz'

str_new = 'xyz'

Answer 1

[Stephen23]

inp = {'$abc_in','def_in_hij_out[]','xyz'}

inp = 1×3 cell array
    {'$abc_in'}    {'def_in_hij_out[]'}    {'xyz'}

out = regexprep(inp,{'_(in|out(\[\])?)?\>','\W+'},'')

out = 1×3 cell array
    {'abc'}    {'def_in_hij'}    {'xyz'}

[kei hin]

What a nice idea !